Note: Descriptions are shown in the official language in which they were submitted.
~197~21
Thls lnventlon relates to a method and apparatus ~or applylng~a
cement mortar or concrete by pro~ectlon, and more partlcularly, by centri-
fu~al force.
Applicatlon of a cement mortar or concrete by blastlng can be
done without preassembling a frame or mold, and lt is not necessary to
dlsassemble the mold after setting of the applied mortar or cement so
that surface finishing can be immediately made. Thus, thls method not
only greaLly simplifies the work, but also ~reatly shortens the working
period. For this reason, ln present days, the method of blastlng ls used
in many cases.
The methods of blasting include the wet method, the dry method
and the semi-wet method. However, thes~ prior art methods are advantageous
in one case but disadvantageous in other cases. More particularly,
according to the blasting method, an hydraulic substance, e.g., cement,
an a8gregate and water are kneaded to prepare a green concrete having
a desired water to cement ratio (W/C), the green concrete
is conveyed to the working field with ~ concrete pump, and
then projected upon a wall surface through a nozzle. With
thi~ method, ~ince cement ~8 sufficiently wetted the ,con-
crete product has a high ~echAn~cal strength. ~owever,where a green concrete of a W/C ratio manifesting the
highest 6trength i8 prepared, such green concrete is
difficult to convey through a conduit becau~e of its high
frictional resistance and high vi3c08ity. Con~equently,
~ pump pre~sure of the order of 50 Kg/cm2 i8 necessary thus
requiring ~ large driving power and ~trong conduit. Even
with such experience the I ~yj- distance of convey~nce i8
at mo~t 50 to 60 m 80 thnt it i8 i ,-~8~ble to apply thl~
~ethod ~or con~u~lng ~ long t. --el. Acoor~l~qly, in
1197;~1
practice, the ratio W/C is increased more or less to impr~ve fluidity of
the green concrete, thus making it impossible fully to take advantage
of the wet method.
On the other hand, according to the dry method, concrete ingredients
are conveyed to the field in a dry state by means of high pressure
air, and the necessary quantity of water is added to the concrete lngre-
dients in a blasting nozzle at the working field. The pressure of the
air necessary to convey the concrete ingredients through a pipe may be
5 - 6 Kg/cm so that the dry method is advantageous to convey the concrete
ingredients over a long distance with a simple and inexpensive installa-
tion. However, kneading of the dry ingredients and water cannot be per-
formed efficiently and cement dust is generated in a great quantity so
that it is impossible to apply kneaded concrete over a long time. More-
over, the mechanical strength of the blasted concrete is only one-half
Of that of the concrete formed by the wet method, which is a serious
defect of the dry method.
The se~i-wet method is an intermediate method in which water
is incorporated at an intermedia`te point of the conveyance pipe instead
of atlthe end thereof. Where water is added at a point 5 to 6 m ahead
at the nozzle, the fluidity decreases greatly, thus clogging the pipe, so
that it is impossible to use a long pipe as in the dry method. Where
water is added at a point close to the nozzle, it is difficult to suffi-
ciently knead the concrete, this difficulty being similar to that encoun-
trered in the dry method.
With anY method, the resulting concrete is blasted to a surface
by means of high pressure air so that concrete once applied onto the surface
tents to be blown away by the blast. A quick setting agent normally used
at the time of blasting is added at the nozzle, but lt is difficult
uniformly to admix the quick setting agent with the concrete whereby the
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i
~1972~1
applied concrete lacks uniformity. Also loss of the quick setting agent
at the time of blasting is high and the lost agent forms a stimulative
atmosphere which makes it difficult to work over a long time. Consider-
ing the shear strength of the blasted concrete layer, in both of the dry
method and the wet method the shear strength is low because in the former
air quantity in the blasted layer is large, while in the latter, the
content of water is high.
Accordingly, it is an object of one aspect of this invention to
provide an improved method and apparatus for applying mortar or concrete
without the accompanying various defects of the prior art methods
described above.
An object of another aspect of this invention is to provide an
improved method and apparatus capable of applying mortar or concrete
without utiliæing pressurized air thus decreasing the generation of dust
and rebound at the working field.
An object of still another aspect of this invention is to pro-
vide a novel method and apparatus capable of uniformly incorporating a
quick setting agent into green mortar or concrete and preventing splash-
ing of the quick setting agent when the green mortar or concrete is applied.
An object of a further aspect of this invention is to provide a
method and apparatus for projecting green concrete capable of independently
adjusting the speed of conveyance of the concrete ingredient and the
speed of the projecting of the green concrete.
An object of a still further aspect of this invention is to
provide an apparatus for projecting green concrete in any desired direc-
tion.
An object of yet another aspect of this invention is to provide an
apparatus capable of projecting green concrete and smoothing the surface
of the applied concrete layer.
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1~97Z~l
According to a broad aspect of this invention, apparatus Is pro-
vided for pro~ecting mortar or concrete comprising a first material supply pipe
for conveying the first material, under pressure, the first material com-
prising one of ehe ingredients of the mortar or concrete; a hopper adapted
to be charged with a second material, the second material comprising the other
ingredient of the mortar or concrete; a second material supply pipe connected
to the hopper; a rotary screw disposed in the second material supply pipe for
mechanically conveying the second material supplied from the hopper; and a
rotary disc for admixing the first material conveyed through the first
material supply pipe, and the second material conveyed through the second
material supply pipe, to project a resulting mixture; the first material sup-
ply pipe, the second material supply pipes and the rotary disc all being
arranged coaxially, and the material supply pipe first and the second material
supply pipe being arranged concentrically with one another.
By one variant thereof, the rotary disc is provided with means for
controlling the direction of projection of the mixture.
By another variant thereof, a discharge end of the second material
supply pipe extends close to the rotary disc, and that discharge end is pro-
vided with a notch for controlling the direction of projection of the mixture.
By a further aspect thereof, the apparatus further includes means
for rotating the second material supply pipe.
By another vari~nt thereof, the rotary disc is provided with means
at the center thereof for agitating the mixture.
By a further variant thereof, the rotary disc comprises an annular
outer ring and a central disc removably mounted in the annular outer ring,
and the agitating means is supported by the central disc.
By a still further variant thereof, the rotary screw is secured to
a periphery of the first material supply pipe, and means are provided for
rotating the first material supply pipe.
~197221
By yet a further variant thereof, the rotary screw is secured to an
inner surface of the second material supply pipe, and means are provided for
rotating the second material supply pipe.
By a still further variant thereof, the first material supply pipe
comprises a main ingredient supply pipe and an auxiliary ingredient supply
pipe.
By a further variant thereof, the rotary disc is provided with annu-
lar projecting means having a projecting surface inclined to the disc.
By a still further variant thereof, the rotary disc is provided with
a plurality of ironing members arranged on a circle having a diameter larger
than the disc for ironing a surface of projected layer.
By yet another variant thereof, the first material comprises a
flowable, slurry material containing water and a powder of hydraulic sub-
stance; and the second material comprises a dry material containing
aggregate.
By yet another variant thereof, the first material comprises a ~uick-
setting agent; and ~ said second material comprises green mortar or con-
cretel
According to another aspect of this invention, a method is provided
for applying mortar or concrete comprising the steps of preparing a first
material and a second material, the materials being necessary to prepare the
mortar or concrete; conveying the first material under pressure through a
first distinct zone to a working field; conveying the second material with
mechanical means through a second distinct zone to the working field; pro-
viding the first distinct zone and the second distinct zone concentrically
within one another; admixing the first material and the second material at
the working field; and projecting the mixture resulting therefrom with a
rotating energy.
; By yet another aspect of this invention, a method is provided of
i
~197ZZl
applying mortar or concrete comprising: providing a first material compris-
ing a flowable, slurry material containing mortar and a powder of hydraulic
substance, and athe second material comprising a dry material containing
aggregate, the first and second materials comprising materials necessary to
prepare the mortar or concrete; conveying the first material under pressure
through a first distinct zone to a working field; conveying the second mater-
ial by mechanical means through a second distinct zone to the working field;
arranging the first distinct one and the second distinct zone to be concen-
tric with one another; admixing the first material and the second material at
the working field; and projecting the resulting mixture by a rotating energy.
By a variant of these aspects, the first material comprises a
quick-setting agent; and the second material comprises green mortar
or concrete.
By a further variant thereof, the first material comprises a quick-
setting agent, and the second material comprises green concrete prepared to
have a predetermined water-to-cement ratio.
By a further variant thereof, the flowable first material com-
prises one,of a cement paste, a green mortar or a green concrete.
By yet another variant thereof, the dry second material comprises a
fine aggregate, or a coarse aggregate, or a combination thereof.
By yet another variant thereof, the flowable first material com-
prises a slurry mortar formed by the steps of: adding a powder of hydraulic
substance to a fine aggregate covered with surface water to form shells of
the hydraulic substance about the fine aggregate; adding water to the fine
aggregate formed with the shells; and then admixing.
In the accompanying drawings,
Figure 1 is a diagrammatic representation showing an apparatus of
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72Zl
one embodiment of this invention utilized to project concrete, and various
devices for preparing ingredients of the concrete;
Figure 2 is a longitudinal sectional view showing an example of a
rotary projecting apparatus showing one embodiment of this invention;
Figure 3 is a side view, partly in longitudinal section, showing a
modified rotary projecting apparatus embodying another embodiment of the
invention;
Figurc 4 is an end view showing a projection direction control
cylinder utilized in the apparatus shown in Figures 2 and 3;
Figures 5A, 5B and 5C are sectional views of an arch type tunnel
in which the inner surface of the tunnel is applied with a concrete coating
by using the apparatus of an embodiment of this invention shown in Figures
2 and 3;
Figure 6 is a side view of a projecting apparatus of an embodiment
of this invention mounted on a carriage and used for projecting concrete;
Figure 7 is a side view, partly in longitudinal section, showing a
modified embodiment of this invention;
Figure 8 is a perspective view showing a base plate of an agitator
utilized in the apparatus of an embodiment of this invention shown in Figure 7;
Figure 9 is a sectional view of a projection direction control de-
vice utilized in the apparatus of an embodiment of this invention shown in
Figure 7;
Figure 10 shows sectional views of an arch type tunnel, the inner
surface thereof being applied with a concrete coating by using the apparatus
of an embodiment of this invention shown in Figure 7;
Figure 11 is a longitudinal sectional view showing modified disc and
agitator utilized in an embodiment of this invention;
~197ZZl
Figure 12 is a side view showing the base plate of the agitator
utilized in the apparatus of an embodiment of this invention shown in Figure 11;
FiKure 13 is a side view, partly in longitudinal section showing
still another modiEication of an embodiment of this invention;
Figures 14 and 15 are diagrammatic representations showing the
apparatus of an embodiment of this invention shown in Figure 13 and various
devices for preparing ingredients of a concrete;
Figure 16 is a diagrammatic representation showing the apparatus
of an embodiment of this invention used for the wet method;
Figure 17 is a longitudinal sectional view showing a modified pro-
jector capable of obliquely projecting green concrete;
Figure 18 is a sectional view of the modified projector shown in
Figure 17;
Figure 19 is a longitudinal sectional view showing still another
modification of an embodiment of this invention; and
Figure 20 is an end view thereof.
The projection apparatus I of an aspect of this invention is util-
ized in a system as shown in Figure 1. The projection apparatus I is connec-
ted to apparatus 2 for preparing a flowable substance, mortar or paste for
example, via pump 5 and conduits. Either one or both of mixers 21 and 22 are
connected with the apparatus 2 through conveyors 7 and 7a of the like. A
cement hopper 24, a sand hopper 23, an additive hopper 25 and a water addition
pipe 26 are provided for the mixer 21, while similar hoppers 23-25, a primary
water addition pipe 26 and a secondary water additisn pipe 27 are provided
for the mixer 22. Dry material preparing devices 3 and 4 are provided for
the projecting apparatus I and dry materials prepared by the devices 2 and 3
are conveyed by conveyors, e.g., belt conveyors 6 and 6a into a hopper 11
provided for the projecting apparatus 1.
` - 8 -
11~7ZZ~.
~ coarsc aggrctate hopper 31, a tine aggregate hopper 32 and a
quick setting agent hopper 33 are mounted above the dry material preparing
device 3, whercas the dry material preparing device 4 is provided with a mixer
40 and above which are mounted a coarse aggregate hopper 41, a fine aggregate
hopper 42 and a quick setting agent hopper 43. Each of the hoppers 23-27,
31-33 and 41-43 is provided with a constant feeder so that predetermined
amounts of the additives are supplied to the preparation devices. Predeter-
mined quantities of the primary water and secondary water are also incor-
porated.
The concrete projection apparatus may be constructed as a carriagc
type, as shown in Figure 2, or as a robot type, as shown in Figure 3. Thc
central pipe 13 (Fig. 2) for conveying flowable materials is connected to a
pipe from the pump 5 which extends in the horizontal direction along the axis
of the projection apparatus 1. The outer end of the central
_ 9 _
i1~7221
pipe 13 is opened toward the center of a rotary disc 18
having a plurality of blades 16. A dry material supply
cylinder 12 concentrically surround~ the central pipe 13,
and a ~crew conveyor 19 extend~ therebetween from the
hopper 11 to the rotary di~c 18. As shown in Fig. 2,
the screw conveyor 19 may be ~ecured to the inner surface
of the supply cylinder 22 which is rotated by a pulley lla
secured thereto and a belt as shown in Fig. 3, the
screw conveyor 19 may be secured to the periphery of the
central pipe 13 which is rotated by an electric motor.
In the latter case, the supply cylinder 12 is held station-
ary. In any case, by the rotation of the screw conveyor 19,
the material supplied from hopper 11 is conveyed to the
rotary disc 18 through the supply cylinder 12. The quantity
of the material ~upplied to the rotary disc 18 i5 propor-
tional to the number of revolutions of the screw conveyor
19 .
The rotary disc 18 is secured to one end of a rotary
cylinder 14 ~urrounding the supply cylinder 12. ~he rotary
cylinder 14 i8 rotated by a pulley 14a ~ecured to the other
end thereof for radially projecting the material on the
rotary disc 18. A pro~ection direction control cylinder 17
i~ pro~ided between the rotary cylin~pr 14 and the supply
cylinder 12 to project toward the rotary blades 16 beyond
the front end of the ~upply cylinder 12. An operatingmember 17~ i8 formed at the oppo~ite end of the cylinder 17
for controlling the direction of pro~ection as shown in
.-
-- 10 --
1197Z21
Fig. 4. Consequently, by adjusting the position of therotary proJ~ction apparatus 1 and the operating member 17a~
it is pos~ible to project concrete onto the inner surface
of nn arch type tunnel having a large or 6mall cro~s-section
a6 shown in Figs. 5A - 5C.
As shown in Figs. 2 and 3, a dish-shaped plate 28 is
~ecured to the center of the rotary disc 18 at a po~ition
confronting the discharge end of the central pipe 13
to receive the flowable slurry material di6charged from
the central pipe 13. The material is then radially and
uniformly discharged from the di~h-shaped plate 28 to be
mixed with dry material supplied by the supply cylinder 12.
Radial blades 16 secured to the periphery of the rotary
diSC 18 impart the desirable projection energy to the mixture
thus formed. The rotary disc 18 and the 6crew conveyor 19
may be rotated at different 6peeds. The 6peed of the
conveyor determines theiquantity of the dry material
supplied to the rotary disc 18, while that of the rotary
disc 18 determine~ the projection energy. Of cour~e,
the quantity of the flowably material through the central
pipe 13 can be varied properly. By a suitable combination
of the~e parameters, any de~ired concrete projection can be
made.
Where a carriage type is adopted as ~hown in Fig. 2,
materials prepared by the preparation device~ 2 and 3 can
also be conveyed to the working field by the carriage.
Such construction i6 ~hown in Fig. 6. More particularly,
~197Z21
a first carriage 101 carries a rotary projector 1, a second
carriage 102 carries a hopper 35 for storing materials
prepared by the dry matexial preparation device i. The
dry material in the hopper 35 is taken out from the bottom
thereof by a take-out mechanigm 36 and is then conveyed to
the projector 1 by conveyors 37 and 37a. A third carriage
103 carries a hopper 55 for storing flowable material
prepared by the flowable material preparation device 2 ~Fig- 1).
An agitator 56 driven by an electric motor 56a is disposed
in the bottom of the hopper 55, and a duct 56b extending
from the agitator 56 is connected to a mortar pump 57
driven by an electric motor 57a, and the central pipe 13
of the projector 1 ic connected to a discharge port 57b
opening at the upper portion of the mortar pump 57.
The projector 1 is mounted on the first carriage 101
via slide blocks 104 which are moved on the first carriage
101 by electric motors 105 to move the projector 1 forwardly or
rearwardly while all carriages 101-103 are stopped,
depending upon the conditions of the working field, for
projecting green concrete upon the surface of a tunnel
just dug. A21 electric motor 115 is mounted on the
first c~rriage 101 for rotating the rotary di3c 18 of
the projector 1, and ~nother motor 116 is mounted for
rotating the screw conveyor 19.
When the apparatus shown in Fig. 6 i~ used for a wet
type concrete working, the carriage 103 ~8 sub~tituted 2~y
a green concrete wagon, ~md the carriage 102 i6 reciprocated
j
_ 12 - ;
between an inlet and the working field in a tunnel ~o a6
to load the green concrete kneaded in the green concrete
waqon into the hopper carried by the carriage 102 at
the inlet of the tunnel. The carriage 102 i~ moved to
S the carriage 101 ~t the working field and the green
concrete is transferred to the carriage 101. In this case,
since the green concrete i5 forced to pa~ through the
central pipe 13 by a pump, it is advantageou~ to increase
the fluidity of the green concre~e. It is advantageous
to convey a green mortar consisting of cement, a fine
aggregate and w~ter through the central pipe 13, while
supplying a dry coarse aggregate and a quick setting agent
fro~ hopper 11. Then, it becomes possible successively to
convey carefully prepared Rreen concrete to the tunnel
inlet by a green concrete w~gon for carrying out the wet
method without installing a concrete mixer in the tunnel.
In a modific2tion ~hown in Fig. 3, the projector 1 is
mounted on an operating base 50 through a ~winging mechanism
51, and the operating ba~e 50 i~ supported by a supporting
arm 52 and an operating cylinder 53, so that the projector
1 can be moved in the vertical direction by the cylinder
53 and ~wung by the swinging mechani~m 51 for projecting
green concrete at a de~ired po6ition ~nd in a desired
direction.
Fig. 7 E~how~; a ~till ar~oth~r embodimcnt of this aspect of this
invention in which the central pipe 13 for ~upplying
flowable material, and the dry ma~erial ~upply cylinder 12
Z~
are disposed concentrically, and dry material~ in the
hopper 11 Are conveyed to the rotary disc 18 by the screw
conveyor 19 in the s~me manner a~ in Figs. 2 and ~. In
this modification, however, an agitator 85 is secured to
the rotary di~c 18 at a pv~ition confronting the discharge
end of the central pipe 13. More particularly, as ~hown
in Fig. 8, the agitator 85 is mounted on the inner side of
a base plate 86 fitted to the central portion of the rotary
disc 18 and provided with a plurality of agitating blades
87 and 88 as 6hown in Fig. 7. The base plate 86 is secured
to the rotary di~c 18 by a bar 89 held by anchors 18a on the
periphery of the rotary disc 18. By depressing a spring
member 89a, the bar 89 is disengaged from the anc~lors 18a
80 that it is possible to dismount the base plate 86 by
grasping handle~ 86a for cleaning or adjusting the agitator
blades 87 and 88. The modification ~hown in Fig. 7 i5
advantageous in that it does not use the cylinder 17 shown
in Figs. 2 and 3 ~o that the direction of projectlng i~
~dju table with a simplified construction. More particu-
larly, the 6upply cylinder 12 surrounds the agitation blades87 and 88 and extends close to the rotary di~c 18. As ~hown
in Fig. 9, portions ~of the cylinder 12 may be removed at 12b
so that, ag the ~.ngular po~ition of the ~upply cylinder 12
is adjusted, the direction of projection c:an be varied,
thu~ enabling projection of green concrete in any de~ired
direction, ~i shown in F~g. 10.
- 14 _
i
~1972Zl
With the agitator shown in Figs. 7 and 8 the agitation is effected
mainly by the blades 87, whereas the blade 88 is slightly inclined with
respect to the axis of the rotary screw l9 for conveying the green concrete
to the rotary disc 18.
Figs. Il and 12 show a modified agitator. In this modification, a
feeder 85a, comprising long and short blades 87a and 87b respectively, is
provided on the inside of the base plate 86 fitted in the central portion of
the rotary disc 18, and an agitation blade 88 is provided at the fore end
of the screw conveyor 19. Each of the blades 87a and 87b is shaped such that
its cross-section gradually decreases in the direction of the conveyance of
the material. Thus, the dry material is conveyed by the screw conveyor l9, is
agitated by blade 88 and is then fed onto the rotary disc 18 by the feeder
85a. The base plate 86 is fastened to the rotary disc 18 by a fastening mem-
ber 89b and bolts 89c on the opposite ends thereof. However, the base plate
86 may be removably secured to the rotary disc as shown in Fig. 8.
Where the green concrete is applied to use a reversible motor for
rotating the rotary cylinder 14 so as to reverse the direction of rotation
of the rotary disc 18. Then, a portion where it is difficult to cover with
concrete when the rotary disc 18 is rotated in one direction can be covered.
As above described according to the apparatus of an aspect of this
invention, it is possible suitably to combine machines installed on the out-
side and inside of a tunnel depending upon the diameter of the tunnel and the
condition of the working field. At a minimum, projector I and preparation
device 4 are installed at the working field and the other machines are in-
stalled on the outside of the tunnel. In one embodiment, pump 5 and flowable
material preparation device 2 can be installed in the tunnel and in a larger
tunnel, other machines can also be installed in the tunnel.
The apparatus of an aspect of this invention can advantageously be
- 15 -
~7ZZ~
used for the conventional projection method. For examplc, in the wet mettlod,
green mortar or green concrete is conveyed through the central pipe 13 by
using a pump as has been described Ln connection with Fig. 6, and gravel is
supplied to the supply cylinder 12 together wi~h a quick setting agent, e.g.,
caustic silicate, calcium chloride, sodium aluminate, or sodium carbonate.
There are added to the flowable substance on the rotary disc 18 and the mix-
ture is then projected. In the conventional wet method, the diameter of the
conduit is decreased at the nozzle and high pressure air is utilized for blast-
ing so that it is necessary to use a pump operating at a high pressure. Even
with such measure, it has been difficult to convey the materials over a long
distance as has been pointed out hereinbefore. According to the apparatus
of an aspect of this invention it is not necessary either to use high pres-
sure air or to reduce the diameter of the conduit near the nozzle, so that it
is possible to convey materials over a long distance with a small pump. More-
over, as the green concrete is projected by the centrifugal force of the
rotary disc, even when the materials are conveyed to the rotary disc at a
relatively low speed, sufficiently large projecting energy can be applied
to the mateFials. When the method and apparatus of aspects of this inven-
tion is applied to the dry method, water is added to a dry mixture by the
screw conveyor in the supply cylinder through the central pipe. When an agi-
tator, e.g. as shown in Fig. 7 or 11, is used, the mixture is thoroughly
admixed to increase the mechanical strength of the projected concrete. More-
over, reflection of the projected concrete is decreased, thus obviating de-
fects of the dry method, while enjoying the advantageous merits thereof.
The utility of the apparatus of an aspect of this invention shown in
Fig. I can be enhanced by providing the device 8 for hoppers 23 and 32 supply-
ing sand or fine aggregate in order to make the surface water on the fine
aggregate uniform. Sand is collected in the river side or sea side and then
; _ 16 -
11~7ZZ~
ls ~ransported to a concrete rnixer. The quantlty and state of water on
thc particlcs of sand vary substantially. For example, evcn with the
sand produccd from thc samc source, when the sand is piled up in a yard,
the quantity of water differs grcatly at the top, bottom and center of
the piLe. Even in the sand sampled at the top, the content of water
is greatly influenced by the weather. More particularly, some of the
sand particles are dry while the others are wet. As is well known in the
art, when preparing a green concrete, the amounts of water and air con-
tained therein have a great influence upon the strength of the resulting
concrcte as well as upon the viscosity and workability of thc green
concrete. According to aspects of this invention, the quantity and state
of water on the sand particles are preferably made uniform for determin-
ing a rational proportion of the ingredients. When the amount of water
on the sand particles is made uniform, the water to cement ratio [W/C]
essential to the preparation of green concrete can be accurately deter-
mined. Regarding the sand-to-cement ratio [S/C] and the sand-to-gravel
ratio [S/A], where the amount of wat`er on the sand particles is made uni-
form, these ratios can also be made accurate. Advanta~eously, cement
powder is first incorporated into sand having a previously adjusted amount
of water to form shells about the sand particles. Such shells contain a
high proportion of cement so that they are stable and would not be broken
during conveyance with a pump and when projected by the rotary disc. More-
over the shells convert irregular sand particles into a spherical form,
which makes it easy to convey with a conveyor. Various methods may be used
to make the quantity of water on the sand particles uniform.
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~197221
According to an aspect of this invention, since the green concrete
$8 project~d against a surface by centrifu~nl force with-
out using any hi~h pressure air,there is little or no sputtering
of the projected concrete caused by.the high pressure air
and the applied concrete i~ compressed by the velocity
energy of subsequently projected green concrete. Although
the flowable slurry material conveyed by a pump has
a sufficiently high fluidity, as i~ is thoroughly admixed
with dry material~ on the rotary disc, the concrete
product after projection has a sufficiently high shear
strength. More particularly, during the admixture, due
to the dry materials the ratio W/C is decreased, while
the ratio S/C or A/C is increa~ed so that the shear strength
of the product can be impro~ed. In other words, a concrete
layer having a sufficient thickness can be formed by
a single projection.
Furthermore, accordlng to an aspect of this invention, the quick_
~etting agent c~n be u~ed mor~ efficiently. ~or example,
when the apparatus of an aspect of this invention is used for the wet
method, the quick-~etting ~gent i~ ~dded i~ a dry state.
In this case, it is possible unifor~ly to admix the quick ~
etting agent with gree~ concrete or green mortar conveyed
through the central pipe 13 by u~ing an agitator as ~hown
in Fig. 7 or 11, ,thu~ o~ing the action of the quick--
~ett~ng ~gent. In the dry method, the qulck--~etting agent
is supplied together with dry lngredients, e.g., cement
powder nnd ~Iggregate. The quick-settlng ~gent will be
. ~ . I
I _ 18 -
~1~7;Z21
uniformly when admixed with dry ingredients until they arrive at the
rotary disc 18. According to the prior art blasting method, immediately
prior to the blasting (that is at the nozzle) as the quick-setting agent
is added to the viscous material with its W/C and S/C ratios suitably
adjusted, particles of thc quick-setting agent would adhere to the surface
of lumpy or particle-shapcd viscous material, thus failing uniformly to
disperse the quick-setting agent. Where high pressure air is used for
blasting, fine particles of the quick-setting agent would float in sur-
rounding atmosphere thus forming a stimulative atmosphere. According to
aspects of this invention as above described, since the quick-setting
agent can be uniformly distributed, and since no high pressure air is
used, the defects described above can be obviated.
When an aggregate formed with cement shells is supplied through
the supply cylinder 12 in a dry state, a relatively low speed quick set-
ting agent is used to prevent setting in the supply tube.
As above described, according to an aspect of this invention,
since the quick-setting agent is uniformly distributed and no high pres-
sure air is used, the quantity of the quick-setting agent can be reduced,
which is not only economical but which also improves the strength of the
resulting concrete structure over a long time.
In a modification shown in Fig. 13, a plurality of material
supply pipes is provided through the central pipe 13. More particularly,
a main ingredient supply pipe 13a and an auxiliary supply pipe 13b are
inserted through the central pipe 13 and these supply pipes are connected
with conduits 130a and 130b respectively.
Materials are supplied to the supply pipes 130a and 130b and to
the hopper 11 in a manner as shown in Fig. 14. More particularly,
materials taken out from the tank 64 are sent to the hopper 11 of the
- 19 -
1~97Z21
projector I via a conveyor 64a, while main and auxiliary materials are
supplied to the supply pipes 13a and 13b in the central pipe 13 from tanks
65 and 66 respectively via flow meters 67 and pump 68. For example,
where a resin concrete is to be pro~ected, a main material of the resin
concrete and a quick-setting agent are contained in the main and auxil-
iary tanks 65 and 67 respectively, and aggregate, e.g. silicate sand or
stone, is discharged from the tank 64.
When the apparatus shown in Fig. 14 is used for coating the
inner surface of a tunnel, tanks 64, 65 and 66, and projector I are in-
stalled in a tunnel A, and a mixture is supplied to the tank A from amixer 70 installed on the outside of the tunnel A. Conventional feeders
71 - 74 are provided for the mixer 70 to supply materials, e.g., cement,
a powder of a quick-setting agent, a fine aggregate e.g. sand, and a
coarse aggregate, e.g., gravel or crushed stone. Water is supplied to
the main tank 65, while a liquid quick-setting agent is supplied to the
auxiliary tank 66. The apparatus of an aspect of this invention can thus
be satisfactorily used for the dry process.
In the foregoing description, although a flowable material, e.g.
cement paste and/or mortar liquid was fed through the central pipe 13 and
a dry aggregate and/or additives were fed through the supply cylinder 12,
it will be clear that the invention in its various aspects is not limited
to such arrangement. Briefly stated, according to aspects of this inven-
tion, in considering the first and second materials necessary to pre-
pared green concrete or mortar to be projected the first material is con-
veyed through the central pipe 13 by means of low pressure air or a pump,
and the second material is loaded into the supply cylinder 12 through
hopper 11 and then mechanically conveyed by means of the screw conveyor 19.
- 20 -
119722~
Finally, these matcrials are admixed and projected by a rotary projector.
Since the central pipe 13 has a smaller diameter than the supply cylin-
der 12 and since the first material is conveyed through the central pipe
under pressure, the first material should have a preselected degree of
fluidity. On the other hand, the second material is not required to be
flowable because it is conveyed to the hopper with a conveyor belt or a
large diameter pipe and then mechanically is conveyed by a screw con-
veyor 19.
Considering these factors, an arrangement shown in Fig. 16 is
suitable for use in the apparatus of an aspect of this invention for the
wet method. The projector I and the preparation device 120 for a quick
setting agen~ are installed in a tunnel, and a green concrete conveyed by
a concrete mixer car 117 is supplied to the hopper 11 by a pump 118 and
a conduit 119 and then is mechanically conveyed by a screw conveyor 19.
Where a liquid quick-setting agent is used, such quick-setting agent is
supplied through the central pipe 13 under its hydrostatic pressure; when
a powdery quick-setting agent is used, such quick-setting agent is con-
veyed by air pressure. The preparation andn conveyance of the materials
are the same as the prior art wet method, and the fluidity of the green
concrete prepared to have a desired ratio W/C is also small. However,
according to an aspect of this invention, only the conveyance of the green
concrete to the hopper 11 is important and no blasting energy is required.
Accordingly, it is possible greatly to reduce the pressure necessary for
conveyance and to increase the length of conveyance.
In the projector shown in Figs. I - 16, the green concrete is
projected in a direction perpendicular to the direction of conveyance.
Figs. 17 and 18 show modified projectors capable of obliquely projecting
the green concrete. In working a tunnel, a framework is generally fabri-
cated with H-shaped steel bars or the like so that with a projector that
~972Zl
projects only in the vertical direction, it is difficult to proJect con-
crete into the frame work. Consequently the projected concrete does not
efficiently bond to the framework. Where a projector, as shown in Fig.
17 or 18 is used, the green concrete can be efficiently projected into
the framework. In the modified projector, an annular auxiliary projec-
tion plate 180 having an inclined guide surface 181 is secured to the
discharge end of the rotary disc 18, the auxiliary projection plate 180
being also provided with blades 186. In the embodiment shown in Fig. 17,
the guide plate 181 is directed forwardly, whereas in the embodiment
shown in Fig. 18, the guide plate 181 is directed rearwardly. It is
advantageous to prepare both types of guide plates, and a selected one
is secured to the rotary disc with set screws 183 and 184. The auxili-
ary projecting plate 180 may be divided into a plurality of sections in
order to facilitate assembly.
When these modified projectors are used, the direction of the
projected green concrete is determined by the guide surface 181 of the
auxiliary projection plate 180 as shown in Fig. 17 so that when a frame-
work is fabricated with H-type stbel stocks 150 on the inner surface of
a tunnel, the concrete is efficiently projected into the framework 150,
thus substantially preventing formation of voids in the projected con-
crete. When the green concrete is to be projected against the opposite
side of the framework, the direction of movement of the apparatus is re-
versed or reciprocated, or the auxiliary projecting plate 180 shown in
Fig. 18 is used. The agitator 85 shown in Fig. 17 is constituted by
blades 87 and 88, which are slightly different from those shown in Figs.
7 and 11, but which operate similarly.
Figs. 19 and 20 show still another embodiment of an apparatus
according to another aspect of this invention especially suitable for use
;
- 22 -
~197Z21
in a circular tunnel to obtain a smooth finished surface. The circular
tunnel has a high pressure resistant property characteristic, and when
water is passed therethrough, it can resist the water pressure. When
a concrete coating is applied by means of a prior art blasting method,
the surface of the blasted concrete layer becomes irregular so that it
is necessary again to blast concrete mortar in order to obtain a smooth
finished surface.
The modification shown in Figs. 19 and 20 is constructed to
minimize or even to eliminate these disadvantages. At first a shell 100
made of a steel plate is applied to the inner surface of a tunnel, and a
carriage 10 supporting a blasting apparatus of an aspect of this inven-
tion is run along rails 113. A green concrete is supplied to the rotary
disc 18 to project the concrete by centrifugal force. Smoothing plates
108 are rotated concentrically with the rotary disc 18 to finish the
surface of the projected concrete layer 128. More particularly, the
rotary disc 18 is mounted on the front end of the rotary cylinder 14 and
is rotated by an electric motor 114 through gears 114a and 14a. A cover
lOa is provided for the front end of the carriage 10, and a large diame-
ter ring gear 109 is rotatably supported by a support lOb in the cover
lOa. A circular disc 107 is secured to the gear 109 through connecting
rods 106. A plurality of supporting members 107a for the smoothing
plate 108 is mounted on the periphery of the disc 107 at an equal spac-
ing, and the smoothing plates 108 are secured to the supporting members
107a by rods 111. A gear 114b driven by the motor 114 engages the inner
gear of the ring gear 109 to drive the same. Rails 113 on which the
carriage 10 runs are embedded in a concrete layer 128 formed by projec-
tion so that these rails act to reinforce the concrete layer.
_ 23 -
~1~7;~21
In addition co various advantag~s d~scrib~d in connection
with Figs. 1 through 18, with the ~mbodim~nt shown in Figs. 19 and 20 th~
smoothing plat~s 108 apply pr~ssure to th~ coated concrete layer in order
smoothly to finish its surface and to make its thickness uniform.
To have a better understanding of aspects of this invention,
the following examples are given, in which all % ar~ weight p~rcent.
Example 1
A batch mixer 22 and the dry material preparing
device 4 were installed on the outside of a tunnel
lo (mixer 21 and preparation device 3 were not used). River
sand was conveyed from a yard 9 and loaded in the hopper~
23 and 42, and No. 6 crushed ~tone was (loaded in the
hopper 41 of ~he batch mixer 40 located on the outside of
the tunnel. Cement was loaded in hopper 24 and a quick
~etting agent was loaded in hopper 43 to prepare material6
to be projected. These material~ were conveyed to the
projector 1 installed in the tunnel and projected against
the inner ~urface thereof having a diameter of 2.2 m.
In this case no cement shell was formed and the mortar
prepared by the mixer 21 had a S/C ~1.5, and W/C ~39%.
~o this mortar were added sand, gravel and a quic,k-setting
- 24 -
1197221
agent supplied from the prcparation device 4 and a green concrete having
S/C=3.7, W/C=43~5%1 S/A=70%, and containing 17.5 Kg/m of the quick-set-
ing agent was obtained. The rate of supply of the mortar through the cen
tral pipe 13 was 2.7 m /hr, while the rate of supply of dry materials by
the screw conveyor was 8,200 Kg/hr. The quantity of projected concrete
was 6.3 m /hr. The pressure of the mortar pump 9 was relatively small,
e.g., of the order of 4 Kg/cm .
The quantity of dust produced in the tunnel, the quantity of re-
bound, and the strength of the resulting concrete are shown in the follow-
ing Table I. After projection for 1.5 hours, no stimulative atmospherewas formed which would have been caused by the sputtering of the quick-set-
ting agent, irrespective of the fact that the diameter of the tunnel was
only 2.2 m.
Example 2
In the same manner as in Example l, mixer 22 and the prepara-
tion device 4 were used, but instead of loading river sand into the mixer
22, sand with its surface water adjùsted to 4/0 by the water content ad-
justing device 8 was loaded in the hopper 42. Thus, the mixer 22 pre-
pared a cement paste having a ratio W/C=35%~ The cement paste was con-
veyed through the central pipe 13, while all quantities of the fine andcoarse aggregates were supplied to the supply cylinder 12. The supply
quantity of the cement paste through the central pipe 13 was greatly re-
duced compared to the quantity of mortar in Example 1, that is, it
- 25 -
1197221
was 1.4 m3/hr, and the cement paste was conveyed
under a pressure of ;~. 8 Xg/cm~. The concrete projected had
W/C ~488, S/A ~60~, S/C -3.3 and contained 350 ~g!m3 of
cement, 1,142 Xg/m3 of sand, 770 Kg~m3 of No. 6 crushed
itone, and 17.5 Kg/m3 of the quick-setting agent.
The quantity of the dust produced is aliso shown in
the following Table I. Since paste was fed through ~he
central pipe, the quantity of dust was increased, but
the quantity of rebound was decreased and the resulting
concrete was found to have a high mechanical strength.
Example 3
The continuous mixer 21 and the preparation device 3
shown in Fig. I w~re used to prepare a fine aggregate formed
with shells (but mixer 22 and the preparation device 4 were
not used). The fine aggregate used was river sand and
its surface water wa~ ad~usted to 4%. This sand was
loaded in hoppers 23 and 32. The same coarse aggregate
and quick-6etting agent as in Example 1 were used. In
mixer 21, cement and the primary water were incorporated
into the 6and from the hopper 23 to form shells containing'
water and cement at a ratio of W/C =18%. Then the 6econdary
water was added through pipe 27 to prepare a cement mortar
having a ratio W/C e39%. The resulting mortar was 6upplied
through the central pipe 13 and, after being Al-' iYecl with
materials ~ent from hopperci 31 -33 via ~upply pipe 12,
the resulting green con~rete was projected. The green
concrete had ratios S/C ~3,7, W/C e43.5% and S/A -70% and
.
_ 26 -
~97ZZ~
contained 17.5 }tg/m3 of the quick--setting agent which was
the same as in Example 1. The torque of the pump S wa~
3 Kg~cm2 which was smaller by 25~ than that of Example 1.
As ~hown in the following Table I, the quantity of
dust was reduced greatly, and the percentage of rebound
was decreased by more than that of Example 2.
Example 4
Cement was added to a mixture of sand having 4~
surface water and No. 6 dry crushed stone to form cement
shells.
The projected green concrete had S/C =2.3, W/C =35%,
S/A =64~ and contained 500 Kg/m3 of cement, 1,135 Kg/m3 of
sand and 550 Kg/m3 of the crushed stone. In this case,
since the coarse aggregate was also for~ed with cement
shells~ the resulting concrete had greater strength than
that Example 3.
The quantity of dust produced was a little larger
than that of Example 3 but was smaller than those of Examples 1
and 2. The quantity of rebound was extremely small. The
green concrete of this Example could be projecte~
in the same manner as that of Example 3.
The quantities of the du~t generated, the percentage
of re~ound formed at the time of projectlng green concrete
of Examples 1 -4~ and the 6trengths of the resulting
concretes are shown in the following Table I. The
quantity of du~t was measured after projecting the green
concrete for 30 minutes without eychAnging ambient air
;
I - 27 -
11~?72Zl
but it was found that ~v~n when the proJ~cting tim~ was incr~s~d b~yon~
30 minutes, the quantity did not change. In contrast, in th~ case of
thc prior art m~thod, the quantity o~ dust reach~d 25 - 30 mg/m after
blasting for 15 minutes, thus making further operation impractical.
This means that the ~ethod and apparatus of various asp~cts of this inv~n-
tion have greatly imp~oved this defect.
Table I
Example Quantity of Rebound Strength (Kg/cm2)
No. (mg/m3) (%~ 7 days after 28 days after
lo 1 3.5 22.0 209 285
2 3.8 12.0 218 293
3 1.6 10.5 240 320
4 2.4 8.5 430 582
Example 5
Batch mixer 22 and dry material preparation device 4
shown in Fig. 1 were in~talled in a tunnel. Mountain 6and
S was used as the fine aggregate,lNo. 7 crushed ~tone as
the coarse aggreg~te and a ~ o~lld consisting essentially
of an alumlnate (known by the Trade ~ark NATOMIC No. 5) as the quick~
~etting agent.
These ingredients were mixed together. In the
flowable material preparation device 2, the mountain sand S,
an ordinary Portland cement C acting a8 a hydraulic powder
and water W were mixed together at weight ratios a8 ~hown
` ~n the ~ollowing Table II.
~1~722~
T~ble II
L~ Fundamental composition/m3
ample
No- Flowable material conveyed by p~mp Dry material
W/C S/C C S . W ~dehydra- S ~ Quick
( g~ ( g) ~ g) tgent(Q) ~Rg) (Rg) agetnt(n96)
47 1.75 350 612.5 161.7 2.8 790.2 357.4 1.0
2 50 2.0 350 700 172.2 2.8 Ç82 345 0
3 50 2.0 350 700 172.2 2.8 682 345 S.0
4 S0 2.0 350 700 172.2 2.8 682 345 7.1
- 29 _
1~97Z~l
The rotary projector shown in Fig. 7 was used. The
rotary disc 18 thereof had ~ diameter of 50 cm and was rotat~d
at a speed of 500 r.p.m~ The quantity of the mortar
conveyed by the mortar pump 5 was 59 Q/min in each Example.
Quantities of the dry materials conveyed by the conveyor
were 140.6 Xg/min in Example 1, and 109.2 Kg/min in Examples
2, 3 and 4. The compositions of the green concrete
projected upon the inner surface of a tunnel. the percentage
of rebound and the strengths of the resulting concrete are
lo shown in the following Table III.
-
-~ - 30 -
Table III
Sample Composition of projected cement/m3 Rebound press(Kon/ s2trength
No. W~C S/C S/A C S G W setting one day 7 days 28 days
(%)(%) (Kg) (Kg1 ~Xg) (Kg) agent (%) after after afte~
(~g)
45.3 4.179.3 360 1495 390 163 3.619.6 - 219.6 251.9
49.2 4.~79.7 356 1438 367 175 0 9.8 65.6 175.4 242.5 ~p
w . ~
,_ .
3 n ~1 1l n n n n 17.818.9 96.6 214.4 265.7 ~v
4 n n n n n n 24.816.9 61.4 175.g 2Zl.9
1197ZZl
As can be noted from this table, the percenrage of the dust
was small in each Example so that the work could be continued after work-
ing for up to two hours or more.
Example 6
The same conditions as in Example 5 were used but the composi-
tion and additives were changed as shown in the following Tablc IV.
- 32 -
11~7221
I I I I I O
-
. _ CO r~ I~ r~l O Ir~ r~l r-- ~ ~r
') c~u~ - ~ r~ ~ N N
I~
r er ~r N
1 N N
p~ N 0~ O N 0~: : N : t CCI a~ N .
- -- ~ o a~ ~o o a:~ ~ N ~
~ U~ I` ~ U~ ~D r-~ r~J ~D
~ a) a ~ ~
~r
- C ~ ,, U) ~
~r ~rl I I I I I I I U~ ' O V ' r-l dP I I I
r~ Q O ~ r-l Ltl
- rC~ ~J O ~J, O Q) -
u -- U -- ~D o
r
~ - V~
H
_ ~
r~l r ~--
Q . . .
CO
~; ' r ~~ N
r3 U
~ O
r
_
r u~
~ o U~ I~ o U~ o o
t4 ~ 1~ N r l N N N N
c~
a, ~ d~ O ~_ ~ O ~ = ~ O
r æ -- ~ u~
N N 1`N N N Ir) In 1
3 tJ~ t-- O r; N 0 : = N ~ ~ U~ Ul
O O ~ O r~ .~
-- N N r~l r~ 1 r~l r 1 r~l N
~O O O O O O
U~ N O U) ~ ~ O ~ ~ I I O
~CO 00 r~~ ~ CD 1~ t~
r l ~D
O
r-- .
O rl N ~ ~rU7 ~D 1~ CD 0~ O r~i N
Z r! r~l r1 r~l
U~
-- 33 --
~1~72Zl
The quantity of the materials supplied to the rotary
disc 18 through central pipe 13, and supply pipe 14, the
number of revolutions of the rotary disc 18 and the com-
position of the green concrete prepared were varied
5 as shown in th~ tol lowing Tabl~ V.
I - 34 _
Table V
D scharged Composition of projected cement (Kg/m3) Number of
Central C S harden- W/C disc 18
(Q/min) (Xg/min) (Xg) (Kg) ~Kg) (Kg) 1 g (rpm)
1 61.6 70 340 1396 407 201 17 59.1 4.1 77.4 soo
2 41.9 87 308 1433 476 172 15.4S5.6 4.7 75.1 n
3 59 140.6 360 1495 390 163 17.345.3 4.1 79,3 n
4 " 109.2 356 1438 367 175 10 49.2 4.0 79.7
59 87 353 1415 387 197 31.155.8 " 78.5 " ,~
6 ~ ~. .. n n n 20.1 600 `~
w 7 ~ " n ~ ~ 28.6 n n n; 7 0 0
8 " 109.2 356 1438 367 175 - 49.2 " 79.7 500
g n 1~ n n
~ n ~ n ~
11 21.6 133 438 1184 515 200 21 45.7 2.7 70.3 n
12 " 127 569.8~093 481 202 9.835.5 1.92 70 "
13 59 109.2 338 1384 358 226 81 66.9 4.1 79.4 n
Remark: In example 13, projector shown in Figs. 11 and 12
was used and its direction of rotation was reversed.
\
:~97~1
The compre6sion strength of the resulting concretes,
the quantity of the dust and th~ perc~ntage of rebound
generated at the time of projecting green concretes of
respective Examples are shown in the following Table VI.
Table VI
Sample Compression strength (Kg/m ) Rebound Dust
No- 7 days after 28 days after (~) (mg/m )
1 169 245 17.6 2.1
2 183 263 19 1.8
3 175 279 12.5 2.0
4 180 251 14.8 2.5
173 232 12.4 1.5
6 215 284 13.3 1.2
7 201 253 10.2 2.3
8 174 226 12.4 1.9
9 193 289 19.9 3.0
221 272 11.9 3.1
11 284 352 12.6 2.3
, 12 389 476 14.8 2.5
! 13 165 253 9.1 2.3
As can be noted from this table the quantity of dust
generated is small in each Example.
-- 3 6
